This invention relates to a field marker for mounting on an agricultural implement for scoring a line in the ground for gauging the distance of subsequent passes in a field.
Various types of field markers are provided in the prior art. One class of marker, known as a disc marker, includes a disc which is carried on the distal end of an extendible arm. When the arm is in a field working position, the disc contacts the ground and scores the earth sufficient for the operator of the farm implement to which it is coupled to follow the path of the previous scoring pass.
Generally, such disc markers includes a mounting assembly which attaches the marker to a farm implement and an arm which is pivotally mounted about an axis along the side of the implement so that the arm can adjust to the varying heights of the ground on which the implement operates. Early in the prior art, the marker was moved into a retracted or transport position by lifting the disc and arm about the pivot axis to a raised position. These simple types of markers often were too long and unintentionally encountered trees and fence rows. If the markers were lifted, they may have even contacted powerlines with fatal results.
Recently, bifold field markers have been developed that have a second axis allowing the marker to fold in half, thus enabling the device to be folded in a more effective and compact manner. These markers were often heavy, expensive, and lacked the ability to adjust to the contours of the ground during operation. Some versions drag along the ground excessively while they are being folded. Those that overly compensate for this problem have difficulty with the downward float of the marker. Further, when these markers fold, they often are difficult to control and flail uncontrollably. Some models require restrictors in their hydraulic hoses to provide for a more docile operation.
For example, U.S. Pat. No. 5,027,525, issued to Haukaas, shows a field marker which can be wing folded. The Haukaas patent discloses a disc marker which folds in an elbow-like fashion and, in its folded position, the distal section of the arm rests alongside the proximal section of the arm through a series of springs, cables and pulleys. Unfortunately, the Haukaas markers requires a shock absorber to stabilize the marker in operation. Further, the Haukaas marker requires a biasing means for regulation of the downward momentum of the marker.